1) Field of the Invention
The present invention relates to a technology for saving energy of a network interface. More particularly, the present invention relates to a network control device and a network control method that control energy saving, an image forming apparatus that includes the network control device, an image forming system that includes the image forming apparatus, and a computer product.
2) Description of the Related Art
Japanese Patent Application Laid-Open No. H11-085420 discloses a printing system for energy saving. In the printing system, a host device and a printer are connected to each other through a network. The printer receives print data transmitted from the host device and prints it out. In the invention, when the printer enters the energy-saving mode, the printer notifies the host device of entering the energy-saving mode. On the other hand, when a button for releasing energy saving is depressed on the host device, the host device transmits data for releasing energy saving to the printer, and the energy-saving mode is released. Disadvantageously, this printing system requires an application for controlling energy saving in the host side.
Japanese Patent Application Laid-Open No. 2002-111927 discloses a facsimile device for energy saving. The facsimile device includes a facsimile communication unit, which performs facsimile communication through at least a public line, and a Local Area Network (LAN) interface (I/F). In the facsimile device, the LAN I/F includes a controller that switches a mode of the facsimile between a normal operation mode, where a program operates at an ordinary clock frequency, and a low-power mode (energy-saving mode), where the clock stops. In the facsimile device, when the LAN I/F receives a seizure signal through the LAN, the facsimile device transits from the energy-saving mode to the normal mode. However, since the seizure signal is set to an IP address of the facsimile device itself, when receiving a packet for the facsimile device, the mode always returns to the normal mode no matter what the packet is. Therefore, the energy saving effect is practically low.